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| United States Patent |
5,683,850
|
|
Matushita
, et al.
|
November 4, 1997
|
Diazo heat-sensitive recording material comprising hydroxy coumarin as a
coupler
Abstract
A diazo heat-sensitive recording material having excellent raw stock
storability and image storage characteristics, which comprises a support
having thereon a recording layer comprising a diazo compound, a coupling
component and an organic base. The diazo compound is a 4-disubstituted
amino-2-alkoxybenzenediazonium salt and the coupling component is a
compound represented by the following general formula:
##STR1##
wherein R.sub.4, R.sub.5, R.sub.6 and R.sub.7 each represents a hydrogen
atom, an alkyl group, an aryl group, an aralkyl group, an alkyloxy group,
an aryloxy group, an alkylthio group, an arylthio group, an acyl group, an
alkoxycarbonyl group, an acyloxy group, a carbamoyl group, a sulfamoyl
group, a halogen atom, a cyano group or a nitro group.
| Inventors:
|
Matushita; Tetunori (Shizuoka, JP);
Sato; Hiroshi (Shizuoka, JP);
Ishige; Sadao (Shizuoka, JP);
Nomura; Kimiatsu (Shizuoka, JP);
Tsurumi; Mitsuyuki (Shizuoka, JP)
|
| Assignee:
|
Fuji Photo Film Co., Ltd. (Kanagawa, JP)
|
| Appl. No.:
|
753886 |
| Filed:
|
December 2, 1996 |
Foreign Application Priority Data
| Current U.S. Class: |
430/138; 430/156; 430/157; 430/171; 430/172; 430/173; 430/182; 430/183; 430/186 |
| Intern'l Class: |
G03C 001/54; G03C 001/58; G03F 007/021 |
| Field of Search: |
430/138,156,157,171,172,173,182,183,186
|
References Cited
U.S. Patent Documents
| 4400458 | Aug., 1983 | Walkow et al. | 430/171.
|
| 4650740 | Mar., 1987 | Usami et al. | 430/171.
|
| 4895826 | Jan., 1990 | Watanabe et al. | 430/138.
|
| 5213939 | May., 1993 | Sugiyama et al. | 430/183.
|
| 5296329 | Mar., 1994 | Sugiyama et al. | 430/182.
|
| 5338642 | Aug., 1994 | Tanaka et al. | 430/182.
|
Primary Examiner: Chu; John S.
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
Claims
What is claimed is:
1. A diazo heat-sensitive recording material comprising a support having
thereon a recording layer comprising a diazo compound, a coupling
component and an organic base, wherein said diazo compound is a diazonium
salt represented by the following general formula (I) and said coupling
component is a compound represented by the following general formula (II):
##STR8##
wherein R.sub.1, R.sub.2 and R.sub.3 each represents an alkyl group, an
aralkyl group or an aryl group; R.sub.2 and R.sub.3 may form a ring
together with the nitrogen atom in formula (I) adjacent to R.sub.2 and
R.sub.3 ; and X represents an acid anion,
##STR9##
wherein R.sub.4, R.sub.5, R.sub.6 and R.sub.7, which may be the same or
different, each represents a hydrogen atom, an alkyl group, an aryl group,
an aralkyl group, an alkyloxy group, an aryloxy group, an alkylthio group,
an arylthio group, an acyl group, an alkoxycarbonyl group, an acyloxy
group, a carbamoyl group, a sulfamoyl group, a halogen atom, a cyano group
or a nitro group; and R.sub.4 and R.sub.5, R.sub.5 and R.sub.6, or R.sub.6
and R.sub.7 may be combined with each other to form a ring.
2. The diazo heat-sensitive recording material as claimed in claim 1,
wherein said recording layer further comprises microcapsules, and said
diazo compound is encapsulated in said microcapsules.
3. The diazo heat-sensitive recording material as claimed in claim 1,
wherein the total number of carbon atoms in R.sub.1, R.sub.2 and R.sub.3
of formula (I) is 12 or more.
4. The diazo heat-sensitive recording material as claimed in claim 1,
wherein the alkyl, aralkyl, or aryl groups represented by R.sub.1, R.sub.2
and R.sub.3 are substituted or unsubstituted.
5. The diazo heat-sensitive recording material as claimed in claim 1,
wherein said diazonium salt represented by formula (I) is represented by
the following general formula (III):
##STR10##
wherein R.sub.8 represents an alkyl group, an aralkyl group or an aryl
group; L.sub.1 and L.sub.2 each represents an alkylene group; A.sub.1 and
A.sub.2 each represents an alkyl group, an aralkyl group, an aryl group,
an alkyloxy group, an aryloxy group, an alkylthio group, an arylthio
group, an acyl group, an alkoxycarbonyl group, an acyloxy group, a
carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a
sulfamoyl group, a halogen atom or a cyano group; L.sub.1 and L.sub.2, and
A.sub.1 and A.sub.2 may each be the same or different; and X represents an
acid anion.
6. The diazo heat-sensitive recording material as claimed in claim 5,
wherein at least one of A.sub.1 and A.sub.2 is an alkoxycarbonyl group, a
carbamoyl group, a sulfamoyl group or a cyano group.
7. The diazo heat-sensitive recording material as claimed in claim 1,
wherein the total number of carbon atoms in R.sub.4, R.sub.5, R.sub.6 and
R.sub.7 in formula (II) is 12 or more.
8. The diazo heat-sensitive recording material as claimed in claim 1,
wherein the compound represented by formula (II) is represented by general
formula (IV):
##STR11##
wherein R.sub.9 represents a hydrogen atom, an alkyl group, an aryl group,
an aralkyl group, an acyl group, an alkoxycarbonyl group, an acyloxy
group, a carbamoyl group, a sulfamoyl group or a halogen atom; R.sub.10,
R.sub.11 and R.sub.12 each represents a hydrogen atom, an alkyl group, an
aryl group, an aralkyl group, an alkyloxy group, an aryloxy group, an
alkylthio group, an arylthio group, an acyl group, an alkoxycarbonyl
group, an acyloxy group, a carbamoyl group or a sulfamoyl group; Y
represents an oxygen atom or a sulfur atom; and l+m is an integer of 1 to
4 with the proviso that m is an integer of 1 or more and n represents an
integer of 1 to 10.
9. The diazo heat-sensitive recording material as claimed in claim 1,
wherein the diazo compound has a melting point of from 30.degree. to
200.degree. C.
10. The diazo heat-sensitive recording material as claimed in claim 1,
wherein said recording layer contains the diazo compound in an amount of
from 0.02 g/m.sup.2 to 3 g/m.sup.2.
11. The diazo heat-sensitive recording material as claimed in claim 1,
wherein said recording layer contains the compound represented by formula
(II) in an amount of from 0.1 to 30 parts by weight per one part by weight
of the diazo compound.
12. The diazo heat-sensitive recording material as claimed in claim 2,
wherein said recording layer further comprises an organic base, and said
compound represented by formula (II) and said organic base are arranged
outside the microcapsules.
13. The diazo heat-sensitive recording material as claimed in claim 1
comprising at least two recording layers, wherein each of said recording
layers contains a diazonium salt represented by formula (I) having a
maximum absorption wavelength different from that of the diazonium salt
contained in the other recording layers.
Description
FIELD OF THE INVENTION
The present invention relates to heat-sensitive recording materials
comprising specific combinations of diazo compounds and couplers as color
developing components, and particularly to red color development type
diazo heat-sensitive recording materials having excellent raw stock
storability prior to recording and excellent image storage characteristics
(light fastness) after recording.
BACKGROUND OF THE INVENTION
Diazo compounds have very high chemical activity, and react with compounds
called couplers such as phenol derivatives or compounds having active
methylene groups to readily form azo dyes. They also are photosensitive,
and are decomposed by light irradiation to thereby lose their activity.
The diazo compounds have therefore been conventionally utilized in light
recording materials to make diazo copies, as described, for example, in
Shashin Kohgaku no Kiso--Higinen Shashin (The Fundamentals of Photographic
Engineering--Nonsilver Photograph), pages 89 to 117 and 182 to 201 (1982),
Corona Publishing Co. Ltd.).
Furthermore, by utilizing the property of light decomposition and resulting
loss of activity, diazo compounds have recently been applied also to
recording materials requiring fixed images. Typical examples of such a
recording material include light-fixing type heat-sensitive recording
materials in which diazo compounds and couplers are heated according to an
image signal and allowed to react with one another to form images,
followed by light irradiation to fix the images, as proposed by Koji Sato
et al., Gazo Denshi Gakkaishi, 11(4), 290-296 (1982), etc.
However, such recording materials use diazo compounds as color forming
elements which are highly active. As a result, the diazo compounds
gradually pyrolyze even in the dark to thereby lose the reactivity.
Therefore, these recording materials disadvantageously have a short shelf
life.
Various methods have been proposed as means for improving the
above-described instability of diazo compounds, and one of the most
effective means includes a method of incorporating the diazo compound into
microcapsules.
Such micro-encapsulation of the diazo compound isolates the diazonium salt
from decomposition enhancers such as water and a base. As a result,
decomposition of the diazo compound is considerably inhibited, and the
shelf life of a recording material employing the encapsulated diazo
compound is also markedly improved, as described in Tomomasa Usami et al.,
Denshi Shashin Gakkaishi, 26(2), 115-125 (1987).
In a general method of encapsulating the diazo compound, a diazonium salt
is dissolved in a hydrophobic solvent (oily phase). The resulting solution
is added to an aqueous solution of a water-soluble polymer (aqueous
phase), followed by emulsification and dispersion with a homogenizer or
the like. In the meantime, a monomer or a prepolymer forming the walls of
the microcapsule is added to either the oily phase or the aqueous phase,
or both, thereby inducing a polymerization reaction or depositing a
polymer at the interface of the oily phase and the aqueous phase to form
polymer walls for the microcapsules.
These methods are described in detail, for example, in Tomohito Kondo,
Microcapsules, Nikkan Kogyo Shinbunsha (1970), and Tamotsu Kondo et al.,
Microcapsules, Sankyo Shuppan (1977), etc.
The walls of microcapsules can be formed from various materials such as
crosslinked gelatin, alginates, cellulose derivatives, urea resins,
urethane resins, melamine resins and nylon resins.
When the microcapsule walls are formed of a material having a glass
transition temperature which is a little higher than room temperature such
as a urea resin and a urethane resin, the capsule walls are impermeable to
substrate at room temperature, whereas they become permeable at the glass
transition temperature or higher. Such microcapsules are therefore called
thermally responsive microcapsules, and are useful for preparing
heat-sensitive recording materials.
That is, the preparation of recording materials in which a heat-sensitive
recording layer comprising diazonium salt-containing thermally responsive
microcapsules, couplers and bases is formed on a support provides for
stable retention of the diazonium salt over a long period of time, easy
formation of color-developed images by heating and also image fixation by
light irradiation.
As described above, micro-encapsulation makes it possible to markedly
improve the stability of the diazo compounds.
On the other hand, 4-substituted amino-2-alkoxybenzene-diazonium salts are
known to exhibit particularly excellent performance as color forming
materials for thermal recording (JP-A-4-59288 (the term "JP-A" as used
herein means an "unexamined published Japanese patent application)), and
to form red dyes having very good hues when subjected to a coupling
reaction with barbituric acid derivatives (JP-A-4-197782).
However, recording materials containing the above-described 4-substituted
amino-2-alkoxybenzenediazonium salts have inadequate raw stock storability
(background coloring properties during storage and before recording) and
insufficient image storage characteristics (light fastness) of developed
color images.
SUMMARY OF THE INVENTION
The present inventors have conducted extensive investigations to solve the
above-described problems of the prior art. As a result, the present
inventors have discovered that the use of diazo compounds having specific
substituent groups in combination with 4-hydroxycoumarin derivatives as a
coupling component provides a very good result, to thereby achieve the
present invention.
Accordingly, an object of the present invention is to provide a
heat-sensitive recording material having excellent raw stock storability
and image storage characteristics using a 4-substituted
amino-2-alkoxybenzenediazonium salt.
The above-objectives of the present invention are attained by a diazo
heat-sensitive recording material comprising a support having thereon a
recording layer comprising a diazo compound, a coupling component and an
organic base, wherein said diazo compound is a diazonium salt represented
by the following general formula (I) and said coupling component is a
compound represented by the following general formula (II):
##STR2##
wherein R.sub.1, R.sub.2 and R.sub.3 each represents an alkyl group, an
aralkyl group or an aryl group; R.sub.2 and R.sub.3 may form a ring
together with the nitrogen atom in formula (I) adjacent to R.sub.2 and
R.sub.3 ; and X represents an acid anion,
##STR3##
wherein R.sub.4, R.sub.5, R.sub.6 and R.sub.7, which may be the same or
different, each represents a hydrogen atom, an alkyl group, an aryl group,
an aralkyl group, an alkyloxy group, an aryloxy group, an alkylthio group,
an arylthio group, an acyl group, an alkoxycarbonyl group, an acyloxy
group, a carbamoyl group, a sulfamoyl group, a halogen atom, a cyano group
or a nitro group; and at least one pair of R.sub.4 and R.sub.5, R.sub.5
and R.sub.6, and R.sub.6 and R.sub.7 may be combined with each other to
form a ring.
DETAILED DESCRIPTION OF THE INVENTION
In general formula (I), the group represented by R.sub.1, R.sub.2 or
R.sub.3 is preferably an alkyl group having 1 to 18 carbon atoms, an
aralkyl group having 7 to 21 carbon atoms or an aryl group having 6 to 20
carbon atoms, which alkyl, aralkyl or aryl group may further have a
substituent group.
In general formula (I) when R.sub.1, R.sub.2 and R.sub.3 are substituted,
examples of useful substituent groups include alkyl, aryl, alkyloxy,
aryloxy, alkylthio, arylthio, acyl, alkoxycarbonyl, acyloxy, carbamoyl,
alkylsulfonyl, arylsulfonyl, sulfamoyl, acylamino and cyano groups and
halogen atoms.
The ring which is optionally formed by R.sub.2 and R.sub.3 together with
the nitrogen atom in formula (I) may be a 5- or 6-membered ring and may
further contain a hetero atom in addition to the nitrogen atom in formula
(I). Examples thereof include morpholino, piperidino, etc.
In general formula (I), the total number of carbon atoms in R.sub.1,
R.sub.2 and R.sub.3 is preferably 12 or more, and particularly preferably
14 or more to provide for oil solubility.
In general formula (I), specific examples of acids of the acid anions
represented by X include polyfluoroalkylcarboxylic acids each having 1 to
9 carbon atoms, polyfluoroalkylsulfonic acids each having 1 to 9 carbon
atoms, boron tetrafluoride, tetraphenylboron, hexafluorophosphoric acid,
aromatic carboxylic acids and aromatic sulfonic acids. Furthermore,
complex compounds can be formed using zinc chloride, cadmium chloride, tin
chloride or the like to stabilize the diazonium salts.
Particularly preferred examples of the compounds represented by general
formula (I) include compounds represented by general formula (III):
##STR4##
wherein R.sub.8 represents an alkyl group, an aralkyl group or an aryl
group; L.sub.1 and L.sub.2 each represents an alkylene group; A.sub.1 and
A.sub.2 each represents an alkyl group, an aralkyl group, an aryl group,
an alkyloxy group, an aryloxy group, an alkylthio group, an arylthio
group, an acyl group, an alkoxycarbonyl group, an acyloxy group, a
carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a
sulfamoyl group, a halogen atom or a cyano group; L.sub.1 and L.sub.2, and
A.sub.1 and A.sub.2 may each be the same or different; and X represents an
acid anion.
Preferred examples of the compounds represented by general formula (III)
include compounds in which at least one of A.sub.1 and A.sub.2 is an
alkoxycarbonyl group, a carbamoyl group, a sulfamoyl group or a cyano
group.
In general formula (II), R.sub.4, R.sub.5, R.sub.6 and R.sub.7 each is
preferably a hydrogen atom, an unsubstituted or substituted alkyl group
having 4 to 36 carbon atoms, an unsubstituted or substituted aryl group
having 6 to 20 carbon atoms, an unsubstituted or substituted aralkyl group
having 7 to 21 carbon atoms, an unsubstituted or substituted alkyloxy
group having 4 to 36 carbon atoms, an unsubstituted or substituted aryloxy
group having 6 to 20 carbon atoms, an unsubstituted or substituted
alkylthio group having 4 to 36 carbon atoms, an unsubstituted or
substituted arylthio group having 6 to 20 carbon atoms, an unsubstituted
or substituted alkoxycarbonyl group having 2 to 25 carbon atoms, an
unsubstituted or substituted acyloxy group having 6 to 20 carbon atoms, an
unsubstituted or substituted carbamoyl group having 2 to 37 carbon atoms,
an unsubstituted or substituted sulfamoyl group having 2 to 35 carbon
atoms, and a halogen atom.
When these groups are substituted, examples of useful substituent groups
include alkyl, aryl, aralkyl, alkyloxy, aryloxy, alkylthio, arylthio,
acyl, alkoxycarbonyl, acyloxy, carbamoyl, sulfamoyl and acylamino groups
and halogen atoms.
Preferred examples of the above-described substituent groups for R.sub.4,
R.sub.5, R.sub.6 and R.sub.7 include alkyl groups each having 1 to 36
carbon atoms, aryl groups each having 6 to 20 carbon atoms, aralkyl groups
each having 7 to 21 carbon atoms, alkyloxy groups each having 1 to 36
carbon atoms, aryloxy groups each having 6 to 20 carbon atoms, alkylthio
groups each having 1 to 36 carbon atoms, arylthio groups each having 6 to
20 carbon atoms, alkylcarbonyl groups each having 2 to 25 carbon atoms,
arylcarbonyl groups each having 7 to 35 carbon atoms, alkoxycarbonyl
groups each having 2 to 25 carbon atoms, acyloxy groups each having 2 to
20 carbon atoms, carbamoyl groups each having 2 to 37 carbon atoms,
acylamino groups each having 2 to 35 carbon atoms, halogen atoms, and a
cyano group.
In general formula (II), the total number of carbon atoms in R.sub.4,
R.sub.5, R.sub.6 and R.sub.7 is preferably 12 or more, and particularly
preferably 14 or more to provide for oil solubility.
The ring which is optionally formed by a pair of R.sub.4 and R.sub.5,
R.sub.5 and R.sub.6, or R.sub.6 and R.sub.7 may be a 5- or 6-membered,
aromatic or nonaromatic ring, and may contain a hetero atom.
Preferred examples of the compounds represented by general formula (II)
include compounds represented by general formula (IV):
##STR5##
wherein R.sub.9 represents a hydrogen atom, an alkyl group, an aryl group,
an aralkyl group, an acyl group, an alkoxycarbonyl group, an acyloxy
group, a carbamoyl group, a sulfamoyl group or a halogen atom; R.sub.10,
R.sub.11 and R.sub.12 each represents a hydrogen atom, an alkyl group, an
aryl group, an aralkyl group, an alkyloxy group, an aryloxy group, an
alkylthio group, an arylthio group, an acyl group, an alkoxycarbonyl
group, an acyloxy group, a carbamoyl group or a sulfamoyl group; Y
represents an oxygen atom or a sulfur atom; l+m is an integer of 1 to 4
with the proviso that m is an integer of 1 or more; and n represents an
integer of 1 to 10.
R.sub.9 is preferably a hydrogen atom, an unsubstituted or substituted
alkyl group having 4 to 36 carbon atoms, an unsubstituted or substituted
aryl group having 6 to 20 carbon atoms or a halogen atom.
R.sub.10, R.sub.11 and R.sub.12 each is preferably a hydrogen atom, an
unsubstituted or substituted alkyl group having 1 to 24 carbon atoms, an
unsubstituted or substituted aryl group having 6 to 20 carbon atoms, an
unsubstituted or substituted aralkyl group having 7 to 21 carbon atoms, an
unsubstituted or substituted alkyloxy group having 4 to 36 carbon atoms,
an unsubstituted or substituted aryloxy group having 6 to 20 carbon atoms,
an unsubstituted or substituted alkylthio group having 4 to 36 carbon
atoms, an unsubstituted or substituted arylthio group having 6 to 20
carbon atoms, an unsubstituted or substituted alkoxycarbonyl group having
2 to 25 carbon atoms, an unsubstituted or substituted acyloxy group having
2 to 20 carbon atoms, an unsubstituted or substituted carbamoyl group
having 2 to 37 carbon atoms, or an unsubstituted or substituted sulfamoyl
group having 2 to 35 carbon atoms.
Y is preferably an oxygen atom.
The diazo compound for use in the present invention preferably has a
melting point of 30.degree. to 200.degree. C., and those having a melting
point of 50.degree. to 150.degree. C. are particularly preferred in terms
of handling.
In the present invention, in order to improve the raw stock storability of
the heat-sensitive recording materials before use, the diazo compound is
preferably encapsulated as described below. In that case, the diazo
compound is dissolved in an appropriate solvent for micro-encapsulation.
Therefore, the diazo compound preferably has an appropriate solubility in
the solvent and a low solubility in water. Specifically, the diazo
compound preferably has a solubility in organic solvents of 5% or more and
a solubility in water of 1% or less.
In the present invention, the heat-sensitive recording layer preferably
contains the diazo compound in an amount ranging from 0.02 g/m.sup.2 to 3
g/m.sup.2, and in terms of color forming density the preferred amount
ranges from 0.1 g/m.sup.2 to 2 g/m.sup.2.
Specific examples of the diazo compounds of the present invention are shown
below, but the present invention should not be construed as being limited
thereto.
##STR6##
The diazo compound represented by general formula (I) may be used either
alone or in a combination of two or more thereof. Furthermore, the diazo
compound represented by general formula (I) can be used in combination
with known diazo compounds depending on the intended application such as
hue adjustment. However, the diazonium salt represented by general formula
(I) preferably account for 50% by weight or more of all diazo compounds
used. Preferred examples of the diazo compounds which can be used in
combination with the diazo compound of formula (I) include
4-diazo-1-dimethylamino-benzene,
4-diazo-2-butoxy-5-chloro-1-dimethylaminobenzene,
4-diazo-1-methylbenzylaminobenzene,
4-diazo-1-ethylhydroxy-ethylaminobenzene,
4-diazo-1-diethylamino-3-methoxybenzene,
4-diazo-1-morpholinobenzene,
4-diazo-1-morpholino-2,5-dibutoxybenzene,
4-diazo-1-tolylmercapto-2,5-diethoxy-benzene,
4-diazo-1-piperazino-2-methoxy-5-chlorobenzene,
4-diazo-1-(N,N-dioctylaminocarbonyl)benzene,
4-diazo-1-(4-tert-octylphenoxy)benzene,
4-diazo-1-(2-ethylhexanoyl-piperidino)-2,5-dibutoxybenzene,
4-diazo-1-›.alpha.-(2,4-di-tert-amylphenoxy)butylpiperidino!benzene,
4-diazo-1-(4-methoxy)phenylthio-2,5-diethoxybenzene,
4-diazo-1-(4-methoxy)benzamido-2,5-diethoxybenzene and
4-diazo-1-pyrrolidino-2-methoxybenzene.
Specific examples of the coupling components of the present invention are
shown below, however, the present invention should not be construed as
being limited thereto.
##STR7##
In the present invention, known coupling components which are coupled with
diazo compounds in a basic system to form dyes can also be used in
combination with the coupling component represented by general formula
(II) for adjusting the hue as needed. However, the coupling component
represented by general formula (II) is preferably used in an amount of 50%
by weight or more based on all the coupling components used.
Details of the preparation of the diazonium salts represented by general
formula (I) and the coupling compounds represented by general formula (II)
are described, for example, in Photographic Science and Engineering 18,
123 (1974) and U.S. Pat. No. 3,463,639.
Examples of known coupling components which can be used in combination with
the coupling component represented by general formula (II) include active
methylene compounds having a methylene group adjacent to a carbonyl group,
phenol derivatives and naphthol derivatives, and specific examples thereof
include resorcin, phloroglucin, sodium
2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid
morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene,
2,3-dihydroxy-6-sulfonaphthalene, 2-hydroxy-3-naphthoic acid
morpholinopropylamide, 2-hydroxy-3-naphthoic acid octylamide,
2-hydroxy-3-naphthoic acid anilide, benzoylacetanilide,
1-phenyl-3-methyl-5-pyrazolone,
1-(2,4,6-trichlorophenyl)-3-anilino-5-pyrazolone,
2-{3-›.alpha.-(2,4-di-ter-amylphenoxy)butaneamido!benzamido}phenol,
2,4-bis(benzoylacetamino)toluene and
1,3-bis(pivaloylacetamino-methyl)benzene.
In the heat-sensitive recording materials of the present invention, the
diazo compound is preferably encapsulated in order to improve raw stock
storability prior to use.
The microcapsules can be prepared by dissolving the diazonium salt and
compounds of the same or different kinds which react each other to form a
polymer substance in a nonaqueous solvent having a boiling point of
40.degree. to 95.degree. C. at ordinary pressure, emulsifying and
dispersing the resulting solution in a hydrophilic protective colloidal
solution, then transferring a wall forming substance to the surfaces of
the oil droplets while removing the solvent by distillation (e.g., by
reducing the pressure of the reaction vessel and elevating the temperature
of the system), and allowing polymer formation to proceed by polyaddition
or polycondensation at the surfaces of the oil droplets to form wall
films.
In the present invention, the use of substantially solvent-free
microcapsules as described below is preferred as providing good shelf
life. Furthermore, the polymer substance forming the walls of the
microcapsules is preferably at least one selected from polyurethane and
polyurea.
Methods for producing microcapsules (with polyurea or polyurethane walls)
containing a diazonium salt for use in the present invention are described
below.
First, a diazonium salt is dissolved in a hydrophobic organic solvent which
forms the cores of the capsules. The organic solvent used in this case is
preferably at least one selected from hydrocarbon halides, carboxylates,
phosphates, ketones and ethers. A polyvalent isocyanate as a wall material
may additionally be added to the core solvent (oily phase).
On the other hand, for an aqueous phase, a water-soluble polymer such as
polyvinyl alcohol or gelatin is dissolved in water to prepare an aqueous
solution. Then, the above-described oily phase is poured thereinto,
followed by emulsifying and dispersing with emulsification means such as a
homogenizer. At this time, the water-soluble polymer acts as a stabilizer
for emulsification and dispersion. In order to more stably conduct
emulsification and dispersion, a surfactant may be added to at least one
of the oily phase and the aqueous phase.
The amount of the polyvalent isocyanate is selected so that the
microcapsules have a mean particle size of 0.3 .mu.m to 12 .mu.m and a
wall thickness of 0.01 .mu.m to 0.3 .mu.m. The size of the dispersed
particles is generally about 0.2 .mu.m to about 10 .mu.m. In the
emulsified dispersion, the polymerization reaction of the polyvalent
isocyanate takes place at the interface of the oily phase and the aqueous
phase to form a polyurea wall.
If a polyol has previously been added to the aqueous phase, the polyvalent
isocyanate can react with the polyol to form a polyurethane wall. In order
to enhance the reaction rate, it is preferable to keep the reaction
temperature high or to add an appropriate polymerization catalyst. The
polyvalent isocyanates, the polyols, the reaction catalysts and polyamines
for forming parts of the walls are described in detail in Polyurethane
Handbook, edited by Keiji Iwata, Nikkan Kogyo Shinbunsha (1987).
The hydrophobic organic solvent in which the above-described diazonium salt
compound is dissolved to form the core of the microcapsules is preferably
an organic solvent having a boiling point of 100.degree. to 300.degree. C.
Specific examples thereof include alkylnaphthalenes, alkyldiphenylethanes,
alkyldiphenylmethanes, alkylbiphenyls, chlorinated paraffin, tricresyl
phosphate, maleates, adipates, sulfates and sulfonates. They may be used
as a mixture of two or more in combination.
When the solubility of the diazonium salt to be encapsulated in these
solvents is poor, a low boiling solvent in which the diazonium salt is
highly soluble can be used in combination therewith. Specific examples
thereof include ethyl acetate, butyl acetate, methylene chloride,
tetrahydrofurane and acetone. When only the low boiling solvent is used to
form the cores of the microcapsules, the solvent evaporates during the
encapsulation reaction to form coreless capsules in which the walls of the
capsules and the diazo compound are integrally present.
The polyvalent isocyanate used as a raw material for the walls of the
microcapsules is preferably a compound having a trifunctional or
higher-functional isocyanate group. However, a difunctional isocyanate
compound may be used in combination therewith. Specific examples thereof
include dimers or trimers (burettes or isocyanurates) of diisocyanates
such as xylene diisocyanate, hydrogenated xylene diisocyanate,
hexamethylene diisocyanate, tolylene diisocyanate, hydrogenated tolylene
diisocyanate, and isophorone diisocyanate, as main raw materials,
multifunctional adducts of these diisocyanates with polyols such as
trimethylolpropane, and condensates of benzene isocyanate with formalin.
Furthermore, the polyol or the polyamine, which is added beforehand to the
hydrophobic solvent forming the cores or to the water-soluble polymer
solution acting as a dispersing medium, can also be used as one of the raw
materials for the walls of the microcapsules. Specific examples of the
polyols and the polyamines include propylene glycol, glycerin,
trimethylolpropane, triethanolamine, sorbitol and hexamethylenediamine.
When the polyol is added, a polyurethane wall is formed.
The water-soluble polymer used in the water-soluble polymer solution thus
prepared in which the oily phase of the capsules is dispersed is
preferably a compound having a solubility in water of 5 g/l or more at a
temperature at which the oily phase is to be emulsified. Specific examples
thereof include polyvinyl alcohol and modified products thereof,
polyacrylic acid amide and derivatives thereof, ethylene-vinyl acetate
copolymers, styrene-maleic anhydride copolymers, ethylene-maleic anhydride
copolymers, isobutylene-maleic anhydride copolymers, polyvinylpyrrolidone,
ethylene-acrylic acid copolymers, vinyl acetateacrylic acid copolymers,
carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch
derivatives, gum arabic and sodium alginate.
These water-soluble polymers preferably have little or no reactivity with
isocyanate compounds. For example, those having reactive amino groups in
their molecular chains such as gelatin must be modified beforehand to
remove this functional group.
Furthermore, when surfactants are added, the addition amount of the
surfactant is preferably 0.1% to 5% based on the weight of the oily phase,
and more preferably 0.5% to 2%.
The emulsification can be conducted by use of a known emulsifying device
such as a homogenizer, a Manton gaulin, an ultrasonic dispersing device or
a Kady mill. After emulsification, the emulsified products are heated to
30.degree. to 70.degree. C. to enhance the capsule wall formation
reaction. Furthermore, in order to prevent coagulation of the capsules,
the collision probability of the capsules is preferably reduced by adding
water, or by adequately stirring during the reaction.
Dispersing agents for preventing coagulation may be newly added during the
reaction. Generation of carbonic acid gas is observed with progress of the
polymerization reaction, and the termination thereof can be considered to
be the approximate end of the capsule wall formation reaction. Usually, a
reaction time of several hours provides the desired diazonium
salt-containing microcapsules.
In the present invention, organic bases are added to enhance the coupling
reaction of the diazo compounds and the couplers. These organic bases can
be used alone or in a combination of two or more thereof. The basic
materials include nitrogen-containing compounds such as tertiary amines,
piperidine derivatives, piperazine derivatives, amidines, formamidines,
pyridine derivatives, guanidine derivatives and morpholine derivatives.
Of these, particularly preferred are piperazine derivatives such as
N,N'-bis(3-phenoxy-2-hydroxypropyl)-piperazine,
N,N'-bis›3-(p-methylphenoxy)-2-hydroxypropyl!-piperazine,
N,N'-bis›3-(p-methoxyphenoxy)-2-hydroxypropyl!-piperazine,
N,N'-bis(3-phenylthio-2-hydroxypropyl)piperazine,
N,N'-bis›3-(.beta.-naphthoxy)-2-hydroxypropyl!piperazine,
N-3-(.beta.-naphthoxy)-2-hydroxypropyl-N'-methylpiperazine and
1,4-bis{›3-(N-methylpiperazino)-2-hydroxy!propyloxy}benzene;
morpholine derivatives such as
N-›3-(.beta.-naphthoxy)-2-hydroxy!-propylmorpholine,
1,4-bis›(3-morpholino-2-hydroxy)propyloxy!-benzene and
1,3-bis›(3-morpholino-2-hydroxy)propyloxy!-benzene;
piperizine derivatives such as
N-(3-phenoxy-2-hydroxypropyl)piperizine and
N-dodecylpiperizine; and guanidine derivatives such as triphenylguanidine,
tricyclo-hexylguanidine and dicyclohexylphenylguanidine.
In the present invention, the coupling component and the basic material
preferably are each used in an amount of 0.1 to 30 parts by weight per one
part by weight of the diazo compound.
In the present invention, color forming auxiliaries can be added to enhance
the color forming reaction, in addition to the above-described organic
bases.
The color forming auxiliaries are substances which increase the developed
color density in thermal recording or lower the minimum color forming
temperature. Also, color forming auxiliaries produce conditions under
which the diazo compound, the basic material, the coupler, etc. readily
react by lowering the melting point thereof or the softening point of the
capsule walls.
The color forming auxiliaries of the present invention can be added to a
heat-sensitive recording layer, for example, so as to conduct heat
development rapidly and safely at low energy. The color forming
auxiliaries include phenol derivatives, naphthol derivatives,
alkoxy-substituted benzene derivatives, alkoxy-substituted naphthalene
derivatives, hydroxy compounds, amide compounds and sulfonamide compounds.
These compounds are considered to lower the melting point of the coupling
component or the basic material, or to improve the heat permeability of
the capsule wall. This makes it possible to realize high developed color
density.
The color forming auxiliaries for use in the present invention also include
thermally fusible substances. The thermally fusible substances are
substances having a melting point of 50.degree. to 150.degree. C. which
are solid at ordinary temperature and melt upon hating to dissolve the
diazo compound, the coupling component, the basic material or the like.
Specific examples of these compounds include carboxylic acid amides,
N-substituted carboxylic acid amides, ketone compounds, urea compounds and
esters.
In the recording material of the present invention, the following known
antioxidants, etc. are preferably used for improving the fastness of the
thermally developed color images against light and heat, or for decreasing
the yellow discoloration of unprinted areas after fixing due to light.
The above-noted antioxidants are described, for example, in EP-A-223739,
EP-A-309401, EP-A-309402, EP-A-310551, EP-A-310552, EP-A-459416, German
Patent Publication (OLS) No. 3435443, JP-A-54-48535, JP-A-62-262047,
JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262,
JP-A-3-121449, JP-A-5-61166, JP-A-5-119449, and U.S. Pat. Nos. 4,814,262
and 4,980,275.
Furthermore, various known additives for heat-sensitive recording materials
and pressure sensitive recording martials are also effectively used.
Specific examples of these additives include the compounds described in
JP-A-60-107384, JP-A-60-107383, JP-A-60-125470, JP-A-60-125471,
JP-A-60-125472, JP-A-60-287485, JP-A-60-287486, JP-A-60-287487,
JP-A-60-287488, JP-A-61-160287, JP-A-61-185483, JP-A-61-211079,
JP-A-62-146678, JP-A-62-146680, JP-A-62-146679, JP-A-62-282885,
JP-A-63-051174, JP-A-63-89877, JP-A-63-88380, JP-A-63-088381,
JP-A-63-203372, JP-A-63-224989, JP-A-63-251282, JP-A-63-267594,
JP-A-63-182484, JP-A-01-239282, JP-A-04-291685, JP-A-04-291684,
JP-A-05-188687, JP-A-05-188686, JP-A-05-110490, JP-A-05-170361,
JP-B-48-043294 (the term "JP-B" as used herein means an "examined Japanese
patent publication") and JP-B-48-033212.
Specific examples thereof include
6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline,
6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline,
6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline,
6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, nickel
cyclohexanoate, 2,2-bis-4-hydroxyphenylpropane,
1,1-bis-4-hydroxyphenyl-2-ethylhexane, 2-methyl-4-methoxydiphenylamine and
1-methyl-2-phenylindole.
The addition amount of the antioxidants is preferably 0.05 to 100 parts by
weight per one part by weight of the diazo compound, and more preferably
0.2 to 30 parts by weight.
The above-described known antioxidants can be contained in the
microcapsules together with the diazo compound, or can be used as a solid
dispersion together with the coupling agent, the basic material and the
other color forming auxiliaries, or as an emulsion together with
appropriate emulsifying auxiliaries, or in both of these forms. The
antioxidants may be used alone or in combination. Furthermore, the
antioxidants may be present or added to the protective layer.
It is not necessary to add antioxidants to the same layer. When used in
combination, these antioxidants are classified into structural types such
as aniline, alkoxybenzene, hindered phenol, hindered amine, hydroquinone,
phosphorus compound and sulfur compound types, and the same or different
types or antioxidants may be used in combination.
The coupling component for use in the present invention, as well as the
basic material and the other color forming auxiliaries, can be solid
dispersed in a sand mill, etc. together with water-soluble polymers.
However, it is particularly preferred to use these components as an
emulsion formed using appropriate emulsifying auxiliaries.
Preferred examples of the water-soluble polymer include the water-soluble
polymers used in preparing the microcapsules (for example, see
JP-A-59-190886). In this case, the coupling component, the basic material
and the color forming auxiliaries are each added to a solution of the
water-soluble polymer to a content of 5 to 40% by weight. The size of the
dispersed or emulsified particles is preferably 10 .mu.m or less.
For reducing yellow discoloration of background areas after fixing, free
radical generators (compounds which generate free radicals by light
irradiation) used in photopolymerizable compositions, etc. can be added to
the recording material of the present invention. Such free radical
generators include aromatic ketones, quinones, benzoin, benzoin ethers,
azo compounds, organic disulfides and acyloxime esters. They are
preferably added in an amount of 0.01 to 5 parts by weight per one part by
weight of the diazo compound.
Similarly, for reducing yellow discoloration, polymerizable compounds
having ethylenic unsaturated bonds (hereinafter referred to as vinyl
monomers) can also be used. The term "vinyl monomer" means a compound
having at least one ethylenic unsaturated bond (such as a vinyl group, a
vinylidene group or the like) in its chemical structure and having a
chemical form of a monomer or a prepolymer. Examples thereof include
unsaturated carboxylic acids and salts thereof, esters of unsaturated
carboxylic acids and polyhydric aliphatic alcohols, and amide compounds of
unsaturated carboxylic acids and polyvalent aliphatic amines.
The vinyl monomers are preferably used in an amount of 0.2 to 20 parts by
weight per one part by weight of the diazo compound.
The above-described free radical generators and vinyl monomers for use in
the present invention can be contained in the microcapsules together with
the diazo compounds.
In the present invention, citric acid, tartaric acid, oxalic acid, boric
acid, phosphoric acid, pyrophosphoric acid, etc. can be added as acid
stabilizers, in addition to the above-mentioned additives.
The recording material of the present invention can be prepared by
providing a coating solution containing the diazo compound-containing
microcapsules, the coupling component, the organic base and other
additives, and by coating a support made of paper or a synthetic resin
film with the coating solution by coating methods such as bar coating,
blade coating, air knife coating, gravure coating, roll coating, spray
coating, dip coating and curtain coating followed by drying, to thereby
form a heat-sensitive layer having a solid content of 2.5 g/m.sup.2 to 30
g/m.sup.2.
In the recording material of the present invention, the microcapsules, the
coupling component, the base, etc. may be arranged either in the same
layer or in different layers of a lamination type recording material.
Furthermore, an intermediate layer can also be provided on the support,
followed by forming a heat-sensitive layer thereon, as described in
JP-A-61-54980.
The support for use in the present invention include neutral paper with a
pH of 5 to 9 sized by a neutral sizing agent such as an alkylketene dimer
(as described in JP-A-56-112383), paper satisfying a relationship between
the Stockigt sizing degree and the metric basis weight and having a Beck
smoothness of 90 seconds or more as described in JP-A-57-116687, paper
having an optical surface roughness of 8 .mu.m or less and a thickness of
30 to 150 .mu.m as described in JP-A-58-136492, paper having a density of
0.9 g/cm.sup.3 or less and an optical contact ratio of 15% or more as
described in JP-A-58-69091, and paper which resists impregnation with a
coating solution and which is made from pulp beaten to a Canadian standard
freeness (JIS P8121) of 400 cc or more, as described in JP-A-58-69097,
paper having improved developed color density and resolution comprising a
glossy coating surface of raw paper made with a Yankee machine as
described in JP-A-58-65695, and paper having improved coating properties
prepared by subjecting raw paper to a corona discharge treatment as
described in JP-A-59-35985, as well as any paper support used in ordinary
pressure sensitive or thermal recording paper and dry or wet diazo copying
paper.
Furthermore, the synthetic resin film used as a support in the present
invention can be selected without particular limitation from known
materials which do not deform on heating during the development procedure
and have dimensional stability. Such films include films of polyesters
such as polyethylene terephthalate and polybutylene terephthalate, films
of cellulose derivatives such as cellulose triacetate, and films of
polyolefins such as polystyrene, polypropylene and polyethylene. These may
be used singly or in a laminated form. The thickness of the support is
from 20 .mu.m to 200 .mu.m.
In the present invention, to prevent sticking and head contamination when
printing on a heat-sensitive recording layer with a thermal head, or to
impart water resistance to the recording material, a protective layer
mainly composed of polyvinyl alcohol, etc. and containing various
pigments, a surface lubricant, etc. (hereinafter referred to as a
protective layer) is preferably further provided on the heat-sensitive
recording layer as needed.
When a recording surface of the diazo heat-sensitive recording material
thus obtained is heated with a thermal head or the like, the capsule walls
of polyurea or polyurethane are softened, and the coupler and the basic
compound outside the capsules enter the capsules to develop color. After
recording, the diazo compound is decomposed by irradiating with light
having a wavelength which is absorbed by the diazo compound. As a result,
the diazo compound loses its reactivity with the coupler to thereby fix
the images.
The light source for fixing includes various fluorescent lamps, xenon
lamps, mercury lamps, etc. It is preferred for efficiently conducting the
light fixation that the emission spectra thereof approximately agree with
the absorption spectra of the diazo compounds used in the recording
materials.
Furthermore, the heat-sensitive recording material of the present invention
can also be exposed through an original to decompose the diazo compound
present in areas other than the image formation areas, thereby forming
latent images, followed by heating to develop the recording material to
obtain images.
The diazo heat-sensitive recording material of the present invention can
also be used as a multicolor heat-sensitive recording material.
Multicolor heat-sensitive recording materials (light-sensitive
heat-sensitive recording materials) are described in JP-A-4-135787,
JP-A-4-144784, JP-A-4-144785, JP-A-4-194842, JP-A-4-247447, JP-A-4-247448,
JP-A-4-340540, JP-A-4-340541 and JP-A-5-34860. Specifically, such
recording materials can be obtained by laminating heat-sensitive recording
layers which develop colors which are different in terms of hue from one
another. Although there is no particular limitation on the layer
constitution, a multicolor heat-sensitive recording material is
particularly preferred in which two heat-sensitive recording layers
(layers B and C) are laminated with a heat-sensitive recording layer
(layer A) comprising an electron donating colorless dye in combination
with an electron accepting compound. The layers B and C comprise two kinds
of diazonium salt compounds differing in sensitive wavelength,
respectively, in combination with couplers. The couplers react with the
respective diazonium salt compounds by heating to develop different color
hues. That is, a first heat-sensitive recording layer (layer A) comprising
the electron donating colorless dye and the electron accepting compound, a
second heat-sensitive recording layer (layer B) comprising a diazonium
salt compound having a maximum absorption wavelength of 360 nm.+-.20 nm
and a coupler which reacts with the diazonium salt compound by heating to
develop color, and a third heat-sensitive recording layer (layer C)
comprising a diazonium salt compound having a maximum absorption
wavelength of 400 nm.+-.20 nm and a coupler which reacts with the
diazonium salt compound by heating to develop color are formed on a
support in this order. In this case, if the developed colors in the
respective heat-sensitive recording layers are selected so as to provide
the three primary colors in subtractive color mixing, namely, yellow,
magenta and cyan, respectively, it is possible to obtain full color image
recording.
When a recording is made on this multicolor heat-sensitive recording
material, the third heat-sensitive recording layer (layer C) is first
heated to react the diazonium salt with the coupler contained therein, to
thereby develop color. Then, the unreacted diazonium salt compound
contained in layer C is decomposed by irradiating with light having a
wavelength of 400 nm.+-.20 nm. Thereafter, heat sufficient to develop
color in the second heat-sensitive recording layer (layer B) is applied to
react the diazonium salt with the coupler contained therein, to thereby
develop color. At this time, layer C is concurrently strongly heated.
However, the diazonium salt compound in layer C has already been
decomposed to lose its color forming ability so that color is not
developed. Furthermore, the diazonium salt compound contained in layer B
is decomposed by irradiating with light having a wavelength of 360
nm.+-.20 nm. Finally, heat sufficient to develop color in the first
heat-sensitive recording layer (layer A) is applied to develop color. At
this time, heat-sensitive recording layers B and C are concurrently
strongly heated. However, the diazonium salt compounds in layers B and C
have already been decomposed to lose their color forming ability so that
color is not developed. The diazo heat-sensitive recording material of the
present invention is preferably used in the form of a multicolor
heat-sensitive recording material as described above.
In the heat-sensitive recording material of the present invention, the
4-substituted amino-2-alkoxybenzenediazonium salts are used as color
formers, so that red-colored images of high quality can be obtained.
Furthermore, the specific combination of the diazonium salt and the
coupler of the present invention improves the light fastness of the
recorded images.
The present invention will be described in greater detail with reference to
the following Examples, which are, however, not to be construed as
limiting the invention.
EXAMPLE 1
Preparation of Capsule Solution A of The Invention
To 19 parts of ethyl acetate, 2.8 parts of (A-4) of this invention and 10
parts of tricresyl phosphate were added and homogeneously mixed therewith.
Then, 7.6 parts of Takenate D-110N (manufactured by Takeda Chemical
Industries Co., Ltd.) was added as a wall forming material to the
resulting mixed solution and homogeneously mixed therewith to obtain
solution I.
Then, 46.1 parts of an 8-wt. % aqueous solution of phthalated gelatin, 17.5
parts of water, and 2 parts of a 10% aqueous solution of sodium
dodecylbenzenesulfonate were added to this solution I, followed by
emulsifying and dispersing at 40.degree. C. and 10000 r.p.m. for 10
minutes. To the resulting emulsified product, 20 parts of water was added
and homogenized. Thereafter, the encapsulation reaction was conducted with
stirring at 40.degree. C. for 3 hours to obtain capsule solution A. The
particle size of the capsules thus prepared was 0.35 .mu.m.
Preparation of Coupling Component/Base Emulsion B
In 10.5 parts of ethyl acetate, 3.0 parts of compound (B-1) described in
this specification as a specific example, 4.0 parts of
1,1-(p-hydroxyphenyl)-2-ethylhexane, 8.0 parts of
4,4'-(p-phenylenediisopropylidene)diphenol, 4.0 parts of
triphenylguanidine, 0.64 part of tricresyl phosphate and 0.32 part of
diethyl maleate were dissolved to obtain solution II.
Then, 49.1 parts of a 15-wt. % aqueous solution of lime-treated gelatin, 9
parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate and 35
parts of water were homogeneously mixed at 40.degree. C., and solution II
was added thereto, followed by emulsifying and dispersing with a
homogenizer at 40.degree. C. and 10000 r.p.m. for 10 minutes. The
resulting emulsified product was stirred at 40.degree. C. for 2 hours to
remove ethyl acetate, and thereafter, the weight of evaporated ethyl
acetate and water was supplemented by adding water to obtain coupling
component/base emulsion B.
Preparation of Coating Solution C
After homogeneous mixing of 6 parts of capsule solution A, 4.4 parts of
water and 1.9 parts of a 15-wt. % aqueous solution of lime-treated gelatin
at 40.degree. C., 8.3 parts of coupling component/base emulsion B was
added to the resulting solution and homogeneously mixed therewith to
obtain coating solution C for a heat-sensitive recording layer.
Preparation of Coating Solution D for a Protective Layer
Thirty-two parts of a 10% aqueous solution of polyvinyl alcohol
(polymerization degree: 1,700, saponification degree: 88%) and 36 parts of
water were homogeneously mixed to obtain coating solution D for a
protective layer.
Coating
A support for photographic printing paper comprising woodfree paper
laminated with polyethylene was coated with solution C for a
heat-sensitive recording layer and coating solution D for a protective
layer with a wire bar and dried at 50.degree. C. in this order to obtain a
desired diazo heat-sensitive recording material. The coated amounts were
6.4 g/m.sup.2 and 1.05 g/m.sup.2 in terms of solid content, respectively.
Test of Color Development and Fixing
Using a thermal head (Type KST, manufactured by Kyocera Corp.), the
electric power to the thermal head and the pulse width were selected so as
to apply a recording energy per unit area of 0 to 40 mJ/mm.sup.2, and
thermal printing was carried out on the diazo heat-sensitive recording
layer to obtain an image. Then, the entire surface was irradiated to light
for 15 seconds using an ultraviolet lamp having an emission center
wavelength of 365 nm and an output of 40 W. The density of the image area
and the background area of the resulting sample was measured with a
Macbeth densitometer.
Light Fastness Test
The above-described color developed and fixed sample was further subjected
to continuous light irradiation for 72 hours with a fluorescent lamp light
fastness tester at 32000 luxes. Discoloration of the image areas and the
background areas were then determined. For image density, changes in
density in which the initial reflection density was about 1.1 were
measured with a Macbeth densitometer.
Comparison Test of Raw Stock Storability
A test of raw stock storability was carried out by measuring the difference
between the developed color density and the background density after
heating with a heat plate, for a diazo heat-sensitive recording sheet
stored at room temperature and one forcedly stored under conditions of
60.degree. C. and 30% RH for 72 hours. The changes in developed color
density were measured with a Macbeth reflection densitometer.
EXAMPLES 2 TO 5
The same procedures as in Example 1 were followed, except that diazonium
compound (A-4) used in capsule solution A in Example 1 was replaced with
(A-5), (A-6), (A-7) and (A-8) of the invention, respectively, to obtain
capsule solutions.
Comparative Example 1
The same procedure as in Example 1 was followed, except that the coupling
component used in Example 1 was replaced with
1-›(n-octadecyl)oxypropyl!-3-phenyl-2,4,6-(1H,3H,5H)-pyrimidinetrione to
obtain a coupling component/base emulsion.
Comparative Examples 2 and 3
The same procedures as in Example 1 were followed, except that the
diazonium salt compound used in Example 1 was replaced with
2-(n-hexyl)oxy-4-{N-›1-methyl-2-(4-methoxyphenoxy)!ethyl,N-n-hexyl}amino-b
enzenediazonium hexafluorophosphate and
2-(n-hexyl)oxy-4-›N-1-methyl-2-phenoxy)ethyl,N-n-hexyl!aminobenzenediazoni
um hexafluorophosphate, respectively, to obtain capsule solutions.
The results obtained in the comparison test of the raw stock storability in
terms of developed color densities and background densities are shown in
Table 1 below.
TABLE 1
______________________________________
Developed Color Developed Color
Density Density
Develop- (Image Area) (Background Area)
ed Color Before After Before
After
Hue Forced Forced Forced
Forced
.lambda.max Storage Storage Storage
Storage
______________________________________
Example 1
530 nm 1.10 1.02 0.10 0.10
Example 2
535 nm 1.10 1.03 0.10 0.10
Example 3
530 nm 1.10 1.01 0.10 0.11
Example 4
525 nm 1.10 1.02 0.10 0.10
Example 5
530 nm 1.10 1.01 0.10 0.10
Comparative
485 nm 1.10 0.97 0.11 0.12
Example 1
Comparative
545 nm 1.10 0.95 0.14 0.22
Example 2
Comparative
545 nm 1.10 0.96 0.21 0.31
Example 3
______________________________________
The image storage characteristics (light fastness) of the color-developed
areas are shown in Table 2 below.
TABLE 2
______________________________________
Developed Color Developed Color
Density Density
(Image Area) (Background Area)
Before After Before After
Light Ir-
Light Ir- Light Ir-
Light Ir-
radiation
radiation radiation
radiation
______________________________________
Example 1
1.10 1.04 0.10 0.10
Example 2
1.10 1.03 0.10 0.10
Example 3
1.10 1.02 0.10 0.11
Example 4
1.10 1.02 0.10 0.11
Example 5
1.10 1.04 0.10 0.11
Comparative
1.10 1.03 0.21 0.24
Example 1
Comparative
1.10 0.83 0.17 0.22
Example 2
Comparative
1.10 0.85 0.24 0.29
Example 3
______________________________________
EXAMPLE 6
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with compound
(B-2). Then, a recording material was prepared, and an image was formed in
the same manner as in Example 1. The densities of the color-developed area
and the background area were measured with a Macbeth densitometer.
EXAMPLE 7
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with compound
(B-4). Then, a recording material was prepared, and an image was formed in
the same manner as in Example 1. The densities of the color-developed area
and the background area were measured with a Macbeth densitometer.
EXAMPLE 8
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was substituted with compound
(B-6). Then, a recording material was prepared, and an image was formed in
the same manner as in Example 1. The densities of the color-developed area
and the background area were measured with a Macbeth densitometer.
EXAMPLE 9
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with compound
(B-8). Then, a recording material was prepared, and an image was formed in
the same manner as in Example 1. The densities of the color-developed area
and the background area were measured with a Macbeth densitometer.
EXAMPLE 10
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with compound
(B-10). Then, a recording material was prepared, and an image was formed
in the same manner as in Example 1. The densities of the color-developed
area and the background area were measured with a Macbeth densitometer.
Comparative Example 4
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with
5-(2-tetradecyloxyphenyl)cyclohexane-1,3-dione. Then, a recording material
was prepared, and an image was formed in the same manner as in Example 1.
The densities of the color-developed area and the background area were
measured with a Macbeth densitometer.
Comparative Example 5
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with
1-phenyl-3-octyloxycarbonyl- pyrazoli-5-one. Then, a recording material
was prepared, and an image was formed in the same manner as in Example 1.
The densities of the color-developed area and the background area were
measured with a Macbeth densitometer.
Comparative Example 6
A coupler/base emulsion was obtained in the same manner as in Example 1,
except that compound (B-1) used in Example 1 was replaced with
N-(2',5'-dibutyloxy-4'-chlorophenyl)-4,4-dimethyl-3-oxopentaamide. Then, a
recording material was prepared, and an image was formed in the same
manner as in Example 1. The densities of the color-developed area and the
background area were measured with a Macbeth densitometer.
The samples thus prepared were evaluated with respect to raw stock
storability, the results of which are set forth in Table 3 below.
TABLE 3
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Developed Color Developed Color
Density Density
Develop- (Image Area) (Background Area)
ed Color Before After Before
After
Hue Forced Forced Forced
Forced
.lambda.max Storage Storage Storage
Storage
______________________________________
Example 6
530 nm 1.10 1.04 0.10 0.11
Example 7
535 nm 1.10 1.03 0.10 0.11
Example 8
536 nm 1.10 1.04 0.10 0.11
Example 9
535 nm 1.10 1.03 0.10 0.11
Example 10
533 nm 1.10 1.03 0.10 0.11
Comparative
480 nm 1.10 0.97 0.10 0.12
Example 4
Comparative
550 nm 1.10 1.03 0.20 0.23
Example 5
Comparative
445 nm 1.10 1.04 0.10 0.13
Example 6
______________________________________
The samples thus prepared were also evaluated with respect to image storage
characteristics (light fastness) of the color-developed areas, the results
of which are set forth in Table 4 below.
TABLE 4
______________________________________
Developed Color Developed Color
Density Density
(Image Area) (Background Area)
Before After Before After
Light Ir-
Light Ir- Light Ir-
Light Ir-
radiation
radiation radiation
radiation
______________________________________
Example 6
1.10 1.05 0.10 0.11
Example 7
1.10 1.06 0.10 0.11
Example 8
1.10 1.08 0.10 0.12
Example 9
1.10 1.05 0.10 0.12
Example 10
1.10 1.06 0.10 0.11
Comparative
1.10 0.51 0.10 0.15
Example 4
Comparative
1.10 0.94 0.20 0.41
Example 5
Comparative
1.10 0.85 0.10 0.12
Example 6
______________________________________
The above results demonstrate that the diazo heat-sensitive recording
material of the present invention comprising a specific diazo compound and
a specific coupling component exhibits excellent raw stock storability
such that the reduction in developed color density is small and the
background whiteness remains high. Furthermore, the above results
demonstrate that the recording material of the present invention provides
excellent image storage characteristics (light fastness) of the
color-developed areas.
While the invention has been described in detail and with reference to
specific examples thereof, it will be apparent to one skilled in the art
that various changes and modifications can be made therein without
departing from the spirit and scope thereof.
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